Coronary heart disease (CHD) is the leading cause of death and disability in postmenopausal women in the United States. Low plasma levels of high-density lipoprotein cholesterol (HDL-C) are a well-established risk factor for CHD. Elevated plasma triglyceride (TG) levels are also a risk factor for CHD in women. HDL particles are heterogeneous in composition (containing apo A-I only, LpAI, or apo A-I and apo A-II, LpAIAII) and charge and size (preBeta1, preBeta2, alpha1-3, preAlpha1-4). Different HDL subpopulations have different physiological functions and therefore may vary in their anti-atherogenic potential. Changes in alpha1 HDL subpopulations are a predictor of coronary disease progression in men. Hormonal replacement therapy (HRT) increases plasma levels of HDL-C, but has adverse effects on TG and C-reactive protein (CRP) levels. While observational studies had indicated a protective role of HRT in CHD, recent intervention studies have shown no CHD protection with the use of HRT. Our preliminary data indicate that there is a large inter-individual variability in HDL subpopulations and TG-rich lipoprotein remnants response to HRT.